Ŏn'er-ōŭs, a.

a. [Lat. onerosus, from onus, oneris, a load, burden; Fr. onéreux, Sp. & It. oneroso.] Burdensome; oppressive. “Too onerous a solicitude.” J. Taylor.

Onerous cause (Scots Law), a good and legal consideration;—opposed to gratuitous.